Myocardial ischemia is typically caused by stenosis of one or more coronary arteries. Treatment of this condition can be accomplished by many different techniques, such as coronary bypass surgery, balloon angioplasty, or laser angioplasty. While these treatments are commonly successful, they are not always feasible. For example, a patient may be too frail to withstand the open-heart surgery required for coronary bypass surgery. In addition, if the stenosis is extremely diffuse or totally occluded, angioplasty may not be possible.
Recently, it has been discovered that myocardial ischemia can be treated by forming channels through the myocardium at the location of the ischemia. This procedure is commonly called transluminal myocardial revascularization (TMR). It is theorized that the channels provide oxygenated blood from the left ventricular lumen to the myocardium, thereby alleviating the ischemia. One way of accomplishing TMR is by using a laser or needle to form channels from the exterior of the heart and through the epicardium, myocardium and endocardium. Another way of forming the channels is by percutaneous access through the aorta such that channels can be formed from the inside of the left ventricular lumen. However, recent studies have demonstrated that these channels do not remain patent, and that the major mechanism for long-term success is angiogenesis.
It has been discovered that the above-described TMR technique results in a small amount of angiogenesis (i.e., formation of new blood vessels) in the heart muscle near the formed channels. These new blood vessels enhance the amount of heart muscle that can take advantage of the increased availability of oxygenated blood.
It can be appreciated that it would be advantageous to further promote angiogenesis in damaged heart muscle in order to enhance the availability of oxygen and nutrients to the muscle.